pong.py

import pygame
import sys

def speed_up_ball():
    global ball_speed_x, ball_speed_y
    
    if ball_speed_x < 0:
        if ball_speed_x > -20:
            ball_speed_x -= 1
            ball_speed_y -= 1

    if ball_speed_x > 0:
        if ball_speed_x < 20:
            ball_speed_x += 1
            ball_speed_y += 1

# Initialize Pygame
pygame.init()

# Set up some constants
WIDTH = 800
HEIGHT = 600
BALL_SIZE = 20
PADDLE_WIDTH = 10
PADDLE_HEIGHT = 100
PADDLE_SPEED = 8
FPS = 60
BALL_SPEED = 5

# Set up the display
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Pong")

# Set up the ball
ball_x = WIDTH / 2
ball_y = HEIGHT / 2
ball_speed_x = BALL_SPEED
ball_speed_y = BALL_SPEED

# Set up the paddles
paddle1_y = HEIGHT / 2 - PADDLE_HEIGHT / 2
paddle2_y = HEIGHT / 2 - PADDLE_HEIGHT / 2

# Set up the point system
score1 = 0
score2 = 0

# Game loop
while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

    # Move the paddles
    keys = pygame.key.get_pressed()
    if keys[pygame.K_w]:
        if paddle1_y > -1:
            paddle1_y -= PADDLE_SPEED
    if keys[pygame.K_s]:
        if paddle1_y < HEIGHT - PADDLE_HEIGHT:
            paddle1_y += PADDLE_SPEED
    if keys[pygame.K_UP]:
        if paddle2_y > -1:
            paddle2_y -= PADDLE_SPEED
    if keys[pygame.K_DOWN]:
        if paddle2_y < HEIGHT - PADDLE_HEIGHT:
            paddle2_y += PADDLE_SPEED

    # Move the ball
    ball_x += ball_speed_x
    ball_y += ball_speed_y

    # Bounce the ball off the walls and paddles
    if ball_y < 0 or ball_y > HEIGHT - BALL_SIZE:
        ball_speed_y *= -1
    elif (ball_y + BALL_SIZE > paddle1_y) and (ball_y < paddle1_y + PADDLE_HEIGHT) and (ball_x < PADDLE_WIDTH):
        ball_speed_x *= -1
        speed_up_ball()
    elif (ball_y + BALL_SIZE > paddle2_y) and (ball_y < paddle2_y + PADDLE_HEIGHT) and (ball_x > WIDTH - PADDLE_WIDTH - 20):
        ball_speed_x *= -1
        speed_up_ball()

    # Check if the ball has gone out of bounds
    if ball_x < -5:
        score2 += 1
        ball_x = WIDTH / 2
        ball_y = HEIGHT / 2
        ball_speed_x = BALL_SPEED
        ball_speed_y = BALL_SPEED
    elif ball_x > WIDTH + 5:
        score1 += 1
        ball_x = WIDTH / 2
        ball_y = HEIGHT / 2
        ball_speed_x = BALL_SPEED
        ball_speed_y = BALL_SPEED

    # Draw everything
    screen.fill((0, 0, 0))
    pygame.draw.rect(screen, (255, 255, 255), (ball_x, ball_y, BALL_SIZE, BALL_SIZE))
    pygame.draw.rect(screen, (255, 255, 255), (0, paddle1_y, PADDLE_WIDTH, PADDLE_HEIGHT))
    pygame.draw.rect(screen, (255, 255, 255), (WIDTH - PADDLE_WIDTH, paddle2_y, PADDLE_WIDTH, PADDLE_HEIGHT))

    # Display the score
    font = pygame.font.Font(None, 36)
    text1 = font.render(str(score1), True, (255, 255, 255))
    screen.blit(text1, (WIDTH / 4, HEIGHT / 2 - 20))
    text2 = font.render(str(score2), True, (255, 255, 255))
    screen.blit(text2, (3 * WIDTH / 4, HEIGHT / 2 - 20))

    # Update the display
    pygame.display.flip()
    pygame.time.Clock().tick(FPS)

Install Python 3 and install pygame, like pip3 install pygame

then you can play pong. My kids love the game!